Artificial satellites have long been in use for space or earth observation, reconnaissance, navigation, communications and scientific measurements. Satellites typically consist of a mission payload and a payload platform or bus. The mission payload performs one or more of the aforementioned functions and the payload platform provides electrical power, thermal management, payload pointing, terrestrial communications, and attitude and orbit control to support the mission payload. Electrical power is typically supplied using solar cells and batteries for power storage and supply when the satellite is in earth's shadow. Thermal management may include heaters when in the earth's shadow, and payload pointing and reflective materials to avoid solar heating. Communications takes place using an omnidirectional antenna between the satellite and ground stations for state of health telemetry, command and control. Finally, most satellites include an attitude determination and control system (ADCS) consisting of sensors and momentum wheels for keeping the satellite pointed in the correct direction and removing residual momentum. In addition to the ADCS, many satellites include an on-board propulsion system for maneuvering and positioning the satellite.
Existing choices for satellite propulsion include monopropellant and bipropellant liquid propellants, cold gas propellants and electric propulsion. Unfortunately, most satellite propulsion systems have significant disadvantages. For example, liquid propellants are frequently toxic, require complex plumbing, valving and pressurization systems and, when firing rocket motors, consume significant power. Cold gas systems, while less complex than liquid propellant systems also require plumbing and valving, have poor mass and delivered impulse efficiency and also require significant power when firing motors. Electric propulsion systems have very high impulse efficiency, but are heavy and typically require very high power levels to operate and produce very low thrust levels.
Thus, it would be advantageous to provide a propulsion system that overcomes many of the above-noted deficiencies.